Epidemiologic studies have demonstrated that non-insulin dependent diabetes mellitus (NIDDM) is associated with 2-4 fold increases in atherosclerotic cardiovascular disease (ASCVD), particularly coronary artery disease (CAD). Hyperlipidemia is a risk factor for ASCVD and CAD in both diabetic and non-diabetic populations, but in contrast to non-diabetics, the most common lipid abnormality in NIDDM is the dyslipidemia of high plasma levels of triglycerides (TG) and low plasma levels of high density lipoprotein (HDL) cholestrol (C). Although low HDL C is an acknowledged risk factor for CAD, high TG has not been shown consistently to be a risk factor. Two possible reasons for the inability to show TG as a risk factor can be cited. First TG levels might only be a weak surrogate for the number of atherogenic very low density lipoproteins (VLDL) in the circulation. VLDL carry most of the TG in the blood but VLDL vary greatly in size and composition, and it is possible that only a subpopulation of VLDL, such as small, cholesteryl ester enriched VLDL, might contribute to ASCVD and CAD. Second, fasting TG, the commonly used measure in epidemiologic studies, might not be as meaningful for risk assessment as postprandial (PP) TG levels. We showed previously that PP TG levels were associated with the presence of exercise-induced ischemia in a non-diabetic population. In the present study, we wish to investigate the role of VLDL subpopulations and PP TG in NIDDM patients with CAD.